Which phase involves atrial contraction pushing blood into the ventricles?

Which phase involves atrial contraction pushing blood into the ventricles?

• A. Atrial systole
• B. Ventricular systole
• C. Isovolumetric contraction
• D. Isovolumetric relaxation

Answer: (A)

The main idea is understanding the timing of the cardiac cycle. Atrial systole is the phase of atrial contraction that actively pushes the remaining blood into the ventricles, finishing ventricular filling just before the ventricles begin to contract. This action increases the ventricular end-diastolic volume and prepares the ventricles for their next beat. It’s distinct from ventricular systole (ventricles contracting), isovolumetric contraction (ventricles contract with all valves closed, no change in blood volume), and isovolumetric relaxation (ventricles relax with valves still closed). So the phase where atrial contraction pushes blood into the ventricles is atrial systole.

The main idea is understanding the timing of the cardiac cycle. Atrial systole is the phase of atrial contraction that actively pushes the remaining blood into the ventricles, finishing ventricular filling just before the ventricles begin to contract. This action increases the ventricular end-diastolic volume and prepares the ventricles for their next beat. It’s distinct from ventricular systole (ventricles contracting), isovolumetric contraction (ventricles contract with all valves closed, no change in blood volume), and isovolumetric relaxation (ventricles relax with valves still closed). So the phase where atrial contraction pushes blood into the ventricles is atrial systole.